New brushless-and e x c i t e r l e s s -type, singlephase and three-phase synchronous generators a r e presented, and the a n a l y s i s of t h e c h a r a c t e r i s t i c s and t h e t e s t r e s u l t s a r e reported. In the three-phase generat o r , the s t a t o r armature winding i s connected e l e c t r ic a l l y with t h e secondary winding of a transformer. I n t h e single-phase generator, t h e s t a t o r i s provided with the armature winding and t h e e x c i t i n g power supplied winding, and t h e armature winding i s e l e c t r i c a l l y connected with the e x c i t i n g power supplied winding through a condenser. I n t h e s e generators, ac e x c i t i n g c u r r e n t flows i n t h e armature winding simultaneously with t h e load current. The r a t i o between t h e number of poles. made by t h e load c u r r e n t and t h a t by t h e ac e x c i t i n g c u r r e n t i s 2 o r 1/2. Thus, t h e generator can be made brushless and e x c i t e r l e s s . The r o t o r of t h e s i n g l ephase generator i s provided with a balanced two-phase f i e l d winding. The r o t o r of t h e three-phase generator i s provided with a bridge type f i e l d winding. In t h i s paper i s shown c i r c u i t c o n s t i t u t i o n s and t h e p r i n c i p l e s f o r such brushless and e x c i t e r l e s s synchronous generat o r s . Steady s t a t e performances of t h e three-phase gene r a t o r s have been analyzed. Experiments f o r these gene r a t o r s have been performed on a 2.0 k W u n i t .
A new self‐excitation scheme has been developed for three‐phase synchronous generators. The generator that uses this scheme behaves as a flat‐compound machine without automatic voltage regulators. The stator of the generator is provided with an armature winding that generates the fundamental and 2nd‐harmonic mmfs. The rotor is equipped with a field winding and a harmonic winding. The harmonic winding is magnetically coupled to the 2nd‐harmonic mmf produced by the armature winding. The current flows in the stator armature winding by way of a three‐phase set of capacitors connected across its three‐phase terminals and the ac voltage is induced in the rotor harmonic winding due to the armature 2nd‐harmonic mmf. By connecting the harmonic winding to the field winding through a rectifier circuit, self‐excitation of the generator is obtained. This excitation scheme is both self‐excited and brushless, and no exciter is required. Additionally, voltage regulation due to load variation can be improved by connecting suitable capacitors.
In this paper the operating principle and circuit configuration of the generator are explained and the experimental results using a 1‐kVA prototype machine are shown. The generator characteristics are theoretically clarified by approximate analysis, and appropriateness of the theory and the usefulness of the proposed scheme are experimentally confirmed.
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